Fast-Drill Method as a Risk-Based Approach to Reduce Deepwater Exploratory Drilling Cost

Abstract

Discovering new oil and gas resources is the key for any energy companies to sustain or improve the hydrocarbon production. However, it is evident that most Exploration & Production (E&P) companies have reduced their exploration investment in recent years and the downturns have contributed to the strain. Therefore, it is critical to choose the strategy and allocate budgets efficiently to make sure the best possible return in the exploration sector. Recently, the Operator restarted the exploration campaign in the deepwater territories of Brunei water, and it was key to leverage the learning curve from the Operator's global experience where essential strategies for cost reduction have been effectively implemented. The Operator has extensive deepwater drilling experience in Asia Pacific region as well as globally, where operational best practices are being replicated in the effort to standardize the Operator's deepwater activities. The Fast-Drill method in the riserless drilling section was identified to be a valuable replication in this part of the globe as it has proven to add values in other regions. The Operator has long concluded that the use of weighted mud (dynamic kill drilling, DKD) in the riserless section contributes considerably to the high cost of subsea exploration drilling. In anticipation of the shallow flow event and to mitigate subsurface uncertainties, the usual Pump-and-Dump method necessitates a substantial contingency volume of DKD mud. To reduce the volume of DKD mud required, the Fast-Drill method was employed instead of the Pump-and-Dump approach. Fast-Drill refers to the method of drilling riserless with seawater at high penetration rates where cutting loadings that are created by fast penetration rates results in the required equivalent circulating density (ECD). The Fast-Drill method has been implemented in two wells in Brunei and the results have been favorable. Among the benefits found were reduced rig time, significantly lower mud costs and the avoidance of gumbo. Borehole stability was maintained, and the hole was cased-off without difficulty. This paper describes the requirements set at the planning stage, to ensure that the project was competitively scoped and that it adhered to the Operator's global standard deepwater operations practices, following a franchise concept. It outlines the challenges encountered and how they were addressed to successfully implement the Fast-Drill approach. Additionally, this paper examines the advantages of this method and illustrates how thorough planning and risk assessment were critical for a safe and efficient execution.